Wild bird habitat duties: guidance for public bodies

Annex 1: Bird Species Assessment by Broad Habitat Type

Approach

1. The latest (fourth) Birds of Conservation Concern (2015) list has been used for this assessment to reflect status and trends of the Red (R), Amber (A) and some Green (G) list species that regularly occur in Scotland. The revised BoCC list can be accessed at:

https://www.britishbirds.co.uk/wp-content/uploads/2014/07/BoCC4.pdf.

This assessment focuses on regularly occurring breeding and wintering species and omits species that are:

a. vagrants;

b. occasional passage migrants;

c. species that do not regularly breed; or

d. rare species that have fewer than 10 breeding pairs.

2. For each species, a broad indication of habitat (coarse level of separation) is given e.g. lowland woodland or upland (managed) habitats. This allows species to be aggregated where possible, though for some species that range over a variety of habitats, or whose habitat requirements are complex, the classification fit may be poor. However, given that action to enhance the conservation status of these species is most likely to operate at the habitat level, this is a necessary simplification. Note though that some species already have targeted action (such as corncrake (R), black grouse (R) and capercaillie (R)).

3. The remainder of this paper is taken up with discussion of these broad habitat groupings and a discussion of the species experiencing a declining population or poor conservation status, and some of the associated factors that may be driving the decline (or poor conservation status). The most recent BoCC (4^th) assessment has seen an increase in the number of species on the Red list, mainly as a result of some species moving from Amber to Red.

4. There are 67 species on the UK Red list of which 9 can be discounted because they do not meet the criteria given above.

5. There are 96 species on the UK Amber list of which 14 can be discounted because they do not meet the criteria given above.

Marine waterfowl and pelagic seabirds

6. There is a significant group of species that forage in the marine environment that are experiencing significant population declines at present. These include three auk species – guillemot (A), razorbill (A) and puffin (R) - as well as kittiwake (R), fulmar (A), Arctic tern (A), great black-backed gull (A) and Arctic skua (R). It includes the passage species, Balearic shearwater (R), which is rare in Scottish waters. There are a number of reasons for the declines seen in species that depend on the marine environment, but broad scale environmental changes in the marine environment are likely to be playing a key role along with specific issues at some locations (predation - especially by invasive non-native species, recreational disturbance, pressure from some fisheries and pollution – especially litter).

7. The UK marine Strategy implements the Marine Strategy Framework Directive. In 2019 the UK assessment of progress towards Good Environmental Status was published which included assessments of marine bird and habitats status. Update of the monitoring programme under the UK Marine Strategy is expected by July 2020, and the programme of measures by December 2021.

Coastal and estuarine species

8. There is a significant group of species, mostly present in the non-breeding season, and foraging in the coastal environment, which are experiencing significant population declines at present. These include dunlin (A), ringed plover (R), redshank (A), turnstone (A), purple sandpiper (A),and a number of seaduck such as long-tailed duck (R), eider (A) and velvet scoter (R). There are a number of disparate reasons for species declines
in the coastal environment including specific issues at some locations (recreational disturbance, habitat loss and pollution) along with climate change effects such as sea level rise that may also be playing a role. Habitat loss to development pressures and increasing recreational disturbance are likely to be key adverse effects in Scottish firths and estuaries. In some situations ‘coastal squeeze’ intensifies pressures on habitat as rising sea levels trap habitats against a fixed landward boundary.

9. Breeding species such as herring gull (R) and ringed plover (R) in coastal habitats are also declining. Reasons for herring gull are unknown but it may be due to changes in their food supply in the inshore marine environment
(e.g. reduction in fishery discards), although herring gull populations in urban environments are believed to be increasing. However, the sustained increase in urban breeding populations adds another layer of complexity to the issue. Ringed plover (R) and breeding tern (e.g. little tern (A)) declines are likely to be at least partly driven by recreational pressures on traditional coastal breeding habitats. Though listed as ‘green’ in the UK list, chough (G) populations are declining in Scotland (breeding is now restricted to Islay).
The species is included here because much of its foraging is done around the coast on cattle grazed pasture.

10. There appears to be little or no commonality in the causes of change and therefore a suite of measures to address species declines will need to be developed to address specific issues.

Lowland farmland

• Farmland birds include characteristic songbird species of cultivated agricultural land as well as breeding wading birds found on wet meadows and other grassland habitats. It also includes wintering goose populations, many of which have seen significant population increases in recent years.
• The decline in lowland farmland bird populations is well known, and population changes for many species in Scotland have mirrored UK-wide trends. However, this is not always the case, and where trends are available separately for Scotland these have been used^[2].
• Many of the declines have been caused by land management changes and the intensification of farming that took place since the 1950s and 60s, such as the loss of mixed farming, a move from spring to autumn sowing of arable crops, change in grassland management (e.g. a switch from hay to silage production), increased pesticide and fertiliser use, and the removal of non-cropped features such as hedgerows.
• Four of the five wader species recently assessed in Scotland (curlew (R), lapwing (R), oystercatcher (G) and redshank (A)) show significant declines, with only snipe (A) showing an increase. The farmland seed-eaters all show stable (skylark (R), yellowhammer (R)) or increasing (linnet (R) and tree sparrow (R)) long-term trends. In the short term, only skylark (R) has a decreasing trend. Targeted management at an appropriate scale can benefit farmland birds. Past declines in corn bunting (R) have been reversed, reflecting the success of targeted management for this species^[3].

11. Other characteristic farmland species that are declining here are grey partridge (R), starling (R), twite (R), corn bunting (R), kestrel (A) and breeding curlew (R) of wet meadows.

12. The reasons for decline in these species are well known and understood for most species. A good recent summary can be found in the following article by Jerry Wilson (Bird Conservation & Lowland Agriculture) in The Changing Nature of Scotland. Reasons for differences between Scotland and the rest of the UK may be related to the greater proportion of spring sown cereals and mixed arable and grassland farms in Scotland, both of which can benefit farmland birds by increasing the availability of winter food and improving the diversity of habitats in the farmed landscape.

13. Measures to address declines may be general (e.g. through agri-environment schemes) or targeted at particular species (e.g. corncrake (R), corn bunting (R)). In particular the Scottish Rural Development Programme will be one of the principal mechanisms to maintain or restore farmland bird populations. For example the Seed Eating Birds Package within SRDP will benefit the suite of species dependent on seed availability over winter.

Lowland woodland species

14. Woodland bird species include those of deciduous, semi-natural woods, commercial (mainly conifer) plantations as well as Caledonian pinewoods and partially wooded heaths. Species characteristic of more upland areas are discussed separately.

15. Woodland bird trends are very mixed. Some species have shown marked increases while others have shown considerable declines. The SNH woodland bird indicator has seen a substantial increase in recent years^[4].

16. Woodland bird populations that have increased hugely, include great spotted woodpeckers (G), which have increased by 530 percent, and chiffchaffs (G), which have increased by 752 percent. The reasons for changes aren’t certain, but changes in how woodland is managed may be starting to help woodland birds. As well, the effect of climate change is making a big difference for some woodland birds in Scotland – improved conditions in their wintering areas have helped chiffchaffs, for example. Willow warblers (A) and tree pipits (R) are also good examples, showing more positive trends in Scotland than further south. Willow warblers (A) have increased
by 46 percent, with tree pipits (R) up 86 percent.

17. Conversely declines in some birds in lowland woodlands have only been recently detected, and there is good evidence to suggest that the rate of such declines and indeed when they started has been slower and later than that for lowland farmland. Species that have shown particular declines include cuckoo (R), linnet (R), marsh & willow tits (R), spotted flycatcher (R), wood warbler (R), mistle thrush (R) and probably pied flycatcher (R). For Caledonian pinewoods, most species appear to be doing well apart from capercaillie (R) with Scottish crossbill (A) moving from the red list to amber.

18. Woodland bird declines are less well understood than those that operate over lowland farmland habitats and may be more diverse and complex^[5]. However, three broad drivers of change have been noted: climate change (e.g. phase shifts in predator and prey phenology); management changes (deer browsing, predators such as squirrels, and changes in woodland harvesting regimes); and factors operating on wintering grounds for long-distance migrants (there is a strong bias in UK data towards long distance migrants in terms of species that are fast decliners). This might imply that for some species at least, management changes at breeding sites may do little to reverse declines.

Lowland marsh & fresh water species

19. Lowland fresh water and marsh habitats include standing and running waters as well as mars (fen) habitats. Upland waters have been included within that habitat grouping. A number of lowland fresh water bodies host large concentrations of wintering waterfowl.

20. Most waterbirds are well monitored by the Wetland Bird Survey (WeBS). Duck and swan numbers have decreased after a relatively stable period and stood at 105% in 2011/12, indicating an upturn since dipping to 98% in 2009/10^[6].

21. There are a number of birds of fresh water and marsh (fen) habitats that are declining, including species such as breeding population of Slavonian grebe (R), as well as commoner breeding and wintering species such as dipper (A), grey wagtail (R), mallard (A) (wintering), pochard (R) (wintering), goldeneye (R) (wintering) and pintail (A). There is some evidence that non-breeding trends may be due to a reduction in the number of continental immigrants into Britain in winter (especially in England which tends to hold the bulk of the UK wintering population). Hence there is a need to distinguish trends in wintering populations from breeding populations and where possible, to disaggregate trend data for England and Scotland.

22. Though red-listed, breeding red-necked phalarope (R) population (mainly confined to Shetland) has seen a recent recovery.

23. Along rivers and streams, numbers of dippers (A) and grey wagtail (R) have also declined, with no clear reason for these changes. In contrast numbers of goosander (G) have probably increased.

24. The causes of species declines are generally poorly understood. While pollution (such as eutrophication) may be involved, many rivers and running waters have seen significant improvement in water quality. Declines in wintering mallard (A) populations are particularly perplexing, especially as breeding populations have increased in recent years. Disturbance from recreational pressure may act at some sites though declines in many wintering species may also reflect adverse changes on breeding grounds.

25. A possible reason for reduced numbers of birds migrating from the continent is thought to be due in part to amelioration of climate and weather on the continent, which favours birds dispersing shorted distance from eastern breeding grounds. In essence this implies that declines are a climate effect and one that there is little overt action needed. However, it should also be noted that UK still acts as an important cold-weather refuge for many continental migrants, and large influxes of wildfowl can and do occur when weather conditions of the continent become largely frozen.

26. Drivers of changes for rarer species (e.g. Slavonian grebe (R)) may be linked to population changes in core breeding populations and climate change (northern species retreating in the face of warmer conditions).

Upland and montane species

27. Upland habitats include a range of environments from the largely unmanaged montane zone to managed game-bird moors, upland wetland ecosystems (the Flows of Caithness & Sutherland) and marginal upland habitats, largely managed as low-intensity agricultural land.

28. There are a number of species found in these environments that have shown significant population declines. In particular a suite of species on moors (breeding ring ouzel (R), curlew (R), whimbrel (R) – notably the previously large Shetland population, meadow pipit (A), whinchat (R), wheatear (A), red grouse (A) and in the montane zone, Eurasian dotterel (R). Species of marginal habitats such as black grouse (R) and grasshopper warbler (R) may also be declining, though there is some uncertainty about both due to sampling and survey difficulties. In the upland fresh water environment, breeding common scoter (R) are declining fast and the residual population is now restricted to two main breeding areas in Western Scotland and the Flow Country.

29. Dotterel (R) populations in the mountains have declined across Scotland. Declines have been particularly significant throughout the margins of its Scottish range and from sites at lower altitudes.

30. There is little consensus and consistency in understanding of the drivers of change. For some species, climate change may be having an impact on habitat suitability and/or prey availability through phase changes in phenology, but extrinsic factors may be responsible for changes in other species e.g. ring ouzel (R), or changes in land management (meadow pipit (A) and red grouse (A)). Loss and degradation of habitat condition and predation (from foxes and crows in particular) have also been linked to declines in some species. The Understanding Predation Report issued by The Moorland Forum highlighted the role that predation may play in population changes of some species. Upland habitats are under pressure from management changes (and lack of management in some areas), changes in grazing pressure, pollution (e.g. orographic nitrogen deposition) and loss of marginal habitats through land improvement and conversion to commercial forestry. Increases in woodland and scrub may also have an adverse impact on open ground species, partly through habitat loss but also through changes in predator management, as this may affect the susceptibility of ground nesting species to mammalian predators.

31. However other species such as tree pipit (R) and willow warbler (A) have shown significant increases in Scotland, contrasting with declines further south. Such changes may be associated with increases in young non-commercial woodland cover.

32. The diversity of drivers of change that operate in upland habitats means that management prescriptions to reverse such changes may need to be site and species specific.

Urban and peri-urban species

• Species such as house sparrow (R), swift (A) and house martin (A) (urban and peri-urban populations are faring badly in many areas). The causes of declines of house sparrow are not well understood and management measures to reverse changes have yet to be developed. Swifts may be vulnerable to loss of potential breeding habitat as buildings are renovated and new houses built, but declines are unlikely to be solely due to urban pressures and may in part, be due to extraneous factors on wintering grounds or on passage.

Issues to bear in mind

33. It should be noted that some species in Scotland have notably different trends to those across UK (so while they may be red-listed they show significant population increases in Scotland – tree pipit (R), cuckoo (R), willow warbler (A)).

34. Species on the red and amber lists have been assigned to broad habitat categories, separated by season as it is likely that most policy and management action required to address changes in populations is likely to be targeted at habitats rather than through single species action plans.

35. There will be exceptions to the above, where action is already being undertaken e.g. capercaillie (R), black grouse (R) and common scoter (A) or where specific management action targeted at that species may be the only reliable means of addressing species’ unfavourable conservation status.